3{40 -Amino-6{40 {0 or 7{40 -(pyrazol-1-yl)fluoran compounds

ABSTRACT

Disclosed are normally substantially colorless chromogenic 3&#39;&#39;amino-6&#39;&#39; or 7&#39;&#39;-(pyrazol-1-yl)fluoran color precursor compounds having the following generic structural formula:   WHEREIN EACH R1 represents either a hydrogen atom or a lower alkyl group having from one to five carbon atoms; wherein each R2 represents either a hydrogen atom, a substituted or unsubstituted lower alkyl group having from one to five carbon atoms or a substituted or unsubstituted phenyl group; and wherein the pyrazolyl group is attached to the fluoran moiety of either the 6&#39;&#39; position or the 7&#39;&#39; position of the latter. These compounds are generally substantially colorless but capable of becoming highly colored when brought into reactive contact with many conventional Lewis acid materials. Accordingly, these compounds are highly useful as a component of pressure-sensitive copying papers.

United StatesPatent [1 1 Alsop [75] inventor: Derek J. Alsop, NorthTonawanda,

[73] Assignee: Moore Business Forms, Inc.,

Niagara Falls, N.Y.

221 Filed: Nov. 21, 1914 211 App]. No.: 525,991

[52] US. Cl. 260/310 R; 428/323 [51] Int. Cl. C07D 231/00 [58] Field ofSearch 260/310 R, 335

[56] References Cited UNITED STATES PATENTS 3,244,728 4/1966 Johnson etal 260/336 3,501.33l 3ll970 Kimura et a]. 260/335 OTHER PUBLICATIONSChemical Abstracts, Vol. 77: 36347x (1972).

Primary Examiner-Donald B. Meyer [5 7 ABSTRACT Disclosed are normallysubstantially colorless chromogenic 3'-amino-6' or7'-(pyrazol-l-yl)fluoran color Dec. 30, 1975 precursor compounds havingthe following generic structural formula:

wherein each R represents either a hydrogen atom or a lower alkyl grouphaving from one to five carbon atoms; wherein each R, represents eithera hydrogen atom, a substituted or unsubstituted lower alkyl group havingfrom one to five carbon atoms or a substituted or unsubstituted phenylgroup; and wherein the pyrazolyl group is attached to the fluoran moietyof either the 6 position or the 7' position of the latter. Thesecompounds are generally substantially colorless but capable of becominghighly colored when brought into reactive contact with many conventionalLewis acid materials. Accordingly, these compounds are highly useful asa component of pressure-sensitive copying papers.

2 Claims, No Drawings 3'-AMlNO-6' OR 7'-(PYRAZOL-l-YL)FLUORAN COMPOUNDSBACKGROUND OF THE INVENTION wherein each R, represents either a hydrogenatom or a lower alkyl group having from one to five carbon atoms;wherein each R, represents either a hydrogen atom, a substituted orunsubstituted lower alkyl group having from one to five carbon atoms ora substituted or unsubstituted phenyl group; and wherein the pyrazolylgroup is attached to the fluoran moiety at either the 6 position or the7 position of the latter.

2. Description of the Prior Art:

impact or pressure sensitive carbonless transfer papers have recentlycome into wide usage in the United States and throughout the world.Ordinarily, such papers are printed and collated into manifolded setscapsble of producing multiple copies. in this connection, pressureapplied to the top sheet causes a corresponding mark on each of theother sheets of the set.

The top sheet of paper, upon which the impact or pressure is immediatelyapplied, ordinarily has its back surface coated with microscopiccapsules containing one of the reactive ingredients which produce amark. A receiver sheet, placed in contact with such back face of the topsheet has its front surface coated with a material having a componentreactive with the contents of the capsules so that when capsules areruptured upon impact by stylus or machine key, the initially colorlessor substantially colorless contents of the ruptured capsules react witha coreactant therefor on the receiver sheet and a mark forms on thereceiver sheet corresponding to the mark impressed by the stylus ormachine key.

in the art, i'm act transfer papers are designated by the terms CB, F8and CF, which stand respectively for "coated back", coated front andback" and coated front". Thus, the CB sheet is usually the top sheet andthe one on which the impact impression is directly made; the CPD sheetsare the intermediate sheets, each of which have a mark formed on thefront surface thereof and each of which also transmits the 2 contents ofruptured capsules from its back surface to the front of the nextsucceeding sheet; and the CF sheet is the last sheet and is only coatedon its front surface to have an image formed thereon. The CF sheet isnot normally coated on its back surface as no further transfer isdesired.

While it is customary to coat the capsules on the back surface and tocoat the co-reactant for the capsules contents on the front surface ofeach sheet, this procedure could be reversed if desired. Further, withsome systems, coatings need not be used at all and the coreactiveingredients may be carried in the sheets themselves, or one may becarried in one of the sheets and the other may be carried as a surfacecoating. Further, the reactants may both comprise microencapsulatedliquids. Patents illustrative of many of the various kinds of systemswhich may incorporate such coreactive ingredients and which may be usedin the production of manifolded transfer papers include, for example,US. Pat. Nos. 2,229,694 to Green, 2,712,507 to Green, 3,016,308 toMacaulay, 3,429,827 to Ruus and 3,720,534 to Macaulay et al.

The most common variety of carbonless impact transfer paper, and thetype with which the compounds of the present invention are preferablyutilized, is the type illustrated, for example, in Green (507) andMacaulay (308) wherein microscopic capsules containing a liquid fillcomprising a solution of an initially colorless chemically reactivecolor forming dye precursor are coated on the back surface of the sheet,and a dry coating of a co-reactantchemical for the dye precursor iscoated on the front surface of a receiving sheet.

Many color precursors useful in connection with carbonless copyingsystems are known to those skilled in the art to which the presentinvention pertains. For example, specific reference is made to the colorprecursors mentioned in the patent to Phillips, Jr. et al., No.3,455,72l and particularly to those listed in the paragraph bridgingcolumns 5 and 6 thereof. A variety of fluoran type color precursors arealso disclosed in U.S. Pat. Nos. 3,50l,33l, 3,6l7,335, 3,669,7l l,3,669,7l2 and 3,697,540 to Kimura et al., in U.S. Pat. Nos. 3,627,787and 3,681,390 to Lin and in U.S. Pat. No. 3,725,4l6 to Yamamoto et al.These materials are capable of reacting with a CF coating containing anacidic material such as the acidieached bentonite-type clay disclosed inabandoned application Ser. No. l2S,075 to Baxter filed Mar. l7, l97l(the entirety of which is hereby specifically incorporated by reference)or the acid-reactant organic polymeric material disclosed in thePhillips, Jr. et al. 72l patent.

Many of the color precursors disclosed in the patents referred to above,are capable of undergoing an acidbase type reaction with an acidicmaterial. Other previously known color precursors are the spiro-dipyrancompounds disclosed in the patent to Harbort, No. 3,293,060 withspecific reference being made to the disclosure of the 060 patentextending from column ll, line 32 through column 12, line 21. The colorprecursors disclosed in the patents listed above are gener allyinitially colorless and are capable of becoming highly colored whenbrought into contact with an acidic layer such as an acid-leachedbentonite-type clay or an acid-reacting polymeric material, or the like.

Generally speaking, the color precursor materials disclosed above aredissolved in a solvent and the solution is encapsulated in accordancewith the procedures and processes described and disclosed by Macaulay(308) and by Green (507) as mentioned above. Other processes forencapsulating color precursors are disclosed in U.S. Pat. No. 3,429,827to Runs and U.S. Pat. No. 3,578,605 to Baxter. [n this connection, itshould be mentioned that the exact nature of the capsule itself is notcritical as long as the same is capable of containing the colorprecursor and can be ruptured by the application of pressure inaccordance with conventional carbonless copying procedures. Solventsknown to be useful in connection with dissolving color precursorsinclude chlorinated biphenyls, vegetable oils (castor oil, coconut oil,cotton seed oil, etc.) esters (dibutyl adipate, dibutyl phthalate, butylbenzyl adipate, benzyl octyl adipate, tricresyl phosphate, trioctylphosphate, etc.), petroleum derivatives (petroleum spirits, kerosene,mineral oils, etc.), aromatic solvents (benzene, toluene, etc.),silicone oils, or combinations of the foregoing. Particularly useful arethe alkylated naphthalene solvents disclosed in U.S. Pat. No. 3,806,463to Konishi et al.

For a disclosure of acidic coatings which are capable of converting thecolor precursors into their highly colored form, reference is made tothe disclosures of U.S. Pat. Nos. 3,622,364, 3,330,722, 3,389,007 and3,293,060, as well as to the disclosure of Baxter application Ser. No.125,075 referred to above.

in the color forming systems outlined above, as will be appreciated bythose skilled in the art, the-color precursors are conventionallycontained in pressure rupturable microcapsules which are included in theback coatings of the sheets of carbonless copying manifolded sets.Further, it will be appreciated that the acidic coatings are generallyutilized as front coatings with the color precursor material in asolvent therefor being transferred from an adjacent back coating to theacidic layer front coating upon rupture of the capsules which containthe color precursor material.

SUMMARY OF THE INVENTION It is an object of this invention to providenew and improved compounds having chromogenic properties and which maybe incorporated in a paper sheet or coated onto the surface thereof toprovide a manifolding unit, and which are, moveover, useful in carryingout improved methods of marking involving reactive contact with acolor-activating material to yield vividly colored reaction products inareas where marking is desired.

It is another object of this invention to provide chromogenic compoundswhich are substantially colorless or only slightly colored offering anew and improved variety of chromogenic characteristics and yieldingnovel vividly colored substances upon contact with color-activatingmaterials.

it is a further object of this invention to provide new and improved,normally substantially colorless, chromogenic substances yieldingcolored reactionproducts when placed in reactive contact with Lewis acidmaterials or the like.

The foregoing objects are achieved by the provision of a family ofsubstantially colorless chromogenic 3'- amino-6 or 7'-(pyrazol-l-yl)fluoran color precursor compounds having the following structuralformula:

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventionis directed to a family of normally substantially colorless chromogenic3'-amino-6' or 7'-(pyrazol-l-yl) fluoran color precursor compoundshaving the following structural formula:

wherein each R represents either a hydrogen atom or a lower alkyl grouphaving from one to five carbon atoms; wherein each R, represents eithera hydrogen atom, a substituted or unsubstituted lower alkyl group havingfrom one to five carbon atoms or a substituted or unsubstituted phenylgroup; and wherein the pyrazolyl group is attached to the fluoran moietyat either the 6' position or the 7' position of the latter. Thesecompounds are substantially colorless; however, when brought intocontact with a solid Lewis acid electron acceptor material such as theacid-leached bentonitetype clay disclosed in the application of Baxter,Ser.

No. 125,075, they may be converted into a highly colored form. Variousother solid acidic materials which are generally capable of convertingthese compounds into their highly colored form are disclosed in U.S.Pat. Nos. 3,622,364, 3,330,722, 3,389,007 and 3,293,060 referred toabove.

The fluoran compounds of the present invention may be prepared byreacting one mole of an appropriate o-(4-amino-2-hydroxybenzoyl)benzoicacid with one mole of an appropriately substitutedl-(hydroxyphenyl)pyrazole compound in the presence of a condensing agentsuch as sulfuric acid, phosphorus pentoxide, polyphosphoric acid or zincchloride and in accordance with the following formula:

wherein R and R, are as defined above; wherein the of Hi (approximately57% HI by weight) and the mixhydroxy group is attached to the phenylgroup of the ture was refluxed for 12 to 16 hours. The reaction pyrazolecompound at either the 3 position or 4 position thereof; and wherein inthe product compound, the pyrazolyl group is attached to the fluoranmoiety at either the 6' position or 7' position of the latter. The

substituted l-(hydroxyphenyl) pyrazole compound may be produced bytreating a corresponding l-(methoxyphenyl)pyrazole compound with Hi andthe l- (methoxyphenyl) pyrazole compound may be produced by reacting amethoxy phenyl hydrazine commixture was allowed to cool to roomtemperature and was then poured into 500 ml of ice water. A sufficientamount of ammonia was added to adjust the pH of the mixture to about8.0, at which time a large quantity of a grey precipitate appeared. Theprecipitate was recovered utilizing a Buchner funnel, was washed withdistilled water until the wash water was neutral and was air dried in anoven at 90 to ll0C. Approximately 30 gms of3,5-dimethyl-l-(S-hydroxyphenyl) pyrazole pound with an appropriatediketone in accordance with eredthe following formula:

H N N 0' 0 ag-c-cH c-R R can.

EXAMPLE I 27.6 gms (0.2 moles) of m-methoxy phenyl hydrazine wereadmixed at room temperature with 20.0 gms (0.2 moles) of acetyl acetoneiii a flask. There was an immediate reaction and thereafter the reactionmixture was heated on a steam bath for about an hour to complete theelimination of water from the 3,5-dimethyl-l-(3- methoxyphenyl) pyrazolethus produced.

EXAMPLE ll 40 gms of 3,5-dimethyl-l-(3-methoxy phenyl) pyrazole producedin accordance with Example I were added to 125 ml of a constant boilingaqueous solution CH5C EXAMPLE III 24.4 gms (0.l3 moles) of3,5-dimethyl-I-(S-hydroxyphenyl) pyrazole produced in accordance withExample ii and 27.0 gms (0.095 moles) of o-(4-diethylamino-2-hydroxybenzoyl) benzoic acid were dissolved in 400 ml of concentrated [4,80]maintained at a temperature of 0 to 10C. Thereafter, the temperature ofthe mixture was raised to room temperature and the reaction waspermitted to proceed for approximately 72 hrs. The reaction mixture wasthen poured into 1.500 ml of ice water and a sufficient amount of a 50%NaOH solution was added to make the overall mixture strongly alkaline(pH of l0-l2). During this period ice was added as required to maintainthe temperature below room temperature. The precipitated solids wereextracted with benzene (3 x 800 ml), treated with activated carbon(Darco) and filtered.

5 Thereafter the benzene was removed by evaporation to obtain 23 gms(approximately 52 percent yield) of 3 '-diethylamino-6'-( 3 ,5-dimethylpyrazoll -yl )fluoran. 1.00 gms of this product were admixedwith 20.0 gms of R-300 solvent (a commercial product of KurehaCorporation of America which is a mixture of isomeric diisopropylnaphthalenes and which is generally disclosed in U.S. Pat. No. 3,806,463to Konishi et al.) and this admixture was warmed slightly on a hot plateuntil a clear solution (solution A) was obtained. Thereafter solution Awas allowed to cool to room temperature. (When a small quantity ofsolution A was applied to an acidic clay coating on a paper substrate, avivid red color appeared.) Then, 3.26 gms of terephthaloyl chloride wereadded to 10.0 gms of R-300 solvent and this mixture was also warmedslightly on a hot plate until a clear solution (solution B) was.obtained. Solution B was then allowed to cool to room temperature.After solutions A and B were prepared, 100 gms of an aqueous solutioncontaining 2.0 weight percent Elvanol' 50-42 (a commercial product of E.l. duPont de Nemours which is a polyvinyl alcohol with 87 to 89%hydrolysis and a viscosity of 35 to 45 cps in a 4% aqueous solution at20C) were placed in a semi-micro Waring blender and then solutions A andB were mixed together at room temperature and the resultant solution wasadded to the Elvanol solution in the blender. The blender was activatedand high shear agitation was continued for about two minutes until anemulsion having a dispersed phase particle size of about 2 to l micronswas obtained. In this emulsion, the aqueous solution containing theElvanol polyvinyl alcohol formed the continuous phase and the solutioncontaining the R-300 solvent, 3'-diethylamino6'-(3,5-dimethylpyrazol-l-yl)fluoran and terephthaloyl chloride formedthe dispersed phase. The emulsion was then transferred to a suitablecontainer such as a beaker and was stirred with a variable speedmechanical stirrer at 300 to 500 rpm while an aqueous solutioncontaining 1.86 gms of diethylentriamlne, L44 gms of sodium carbonateand ml of water was added. Stirring was continued at room temperaturefor about 24 hours until a stable pH of about 8.0 was observed. At thistime, the particles of dispersed phase had become individuallyencapsulated in a polyamide shell. The slurry containing themicrocapsules, and having the Elvanol polyvinyl alcohol binder in thecontinuous phase, was then drawn down on a 13 pound neutral basecontinuous bond paper sheet at a coating weight of approximately 2.34 to3.04 grns per square meter and the coated sheet was oven dried at atemperature of l 10C for about 30 to 45 seconds. The dry coating on thepaper sheet was white. The dry coating of microcapsulespyryazol-l-yl)fluoran was then brought into contact with an acid-leachedbentonite-type clay coating on the surface of another sheet of paper andwhen an impression was made on the reverse side of the sheet coatedcontaining 3'-diethylamino-6'-(3,5-dimethylwith microcapsules, acorresponding red colored reproduction of such impression immediatelyappeared on the acid-leached bentonite-type clay coating.

While the foregoing Example specifically discloses the production anduse of 3'-diethylamino-6'-(3,5- dimethylpyrazol-l-yl)fluoran, it ispointed out that the present invention contemplates and specificallyencompasses the similar production and use of 3'-amino- 6' or7'-(pyrazol-l-yl)fluoran compounds as disclosed above wherein the aminonitrogen atom carries either hydrogen atoms, methyl groups, ethylgroups, propyl groups, butyl groups, pentyl groups or any mixture of twoof the foregoing and wherein the pyrazolyl group carries, at each of its3 and 5 positions, either a hydrogen atom, a substituted orunsubstituted lower alkyl group having from one to five carbon atoms ora substituted or unsubstituted phenyl group.

Moreover, other solvents for color precursors are known to those skilledin the art to which this invention pertains and any solvent for3'-amino-6' or 7'-(pyrazoll-yl)fluoran compounds which does notsubstantially interfere with the formation of color when the compound iscontacted with a co-reactant may be utilized. Specifically, it should benoted that dibutyl phthalate may be utilized as a solvent for the colorprecursors of the present invention. it should be appreciated that thecompounds of the present invention are useful generally in theproduction and generation of colored marks and it is not critical to thepresent invention that the same be utilized in a copying system or in amicroencapsulated form.

I claim:

1. A chromogenic 3'-amino-(pyrazol-l-yl) fluoran compound having thefollowing structural formula:

Il Rt

1. A CHROMOGENIC 3''-AMINO-(PYRAZOL-1-YL) FLUORAN COMPOUND HAVING THE FOLLOWING STRUCTURAL FORMULA:
 2. A chromogenic fluoran compound as set forth in claim 1 wherein said compound is 3''-diethylamino-6''-(3,5-dimethylpyrazol-1-yl) fluoran. 